The present disclosure relates to a conveying roller that conveys a sheet, and to a feeding unit and an image forming apparatus provided with such a conveying roller.
In conventional image forming apparatuses such as copiers and printers, many conveying rollers are provided as a means for conveying sheets. A conveying roller is composed of, for example, a roller member for conveying a sheet by rotating while in contact with the sheet, and a rotary shaft to which the roller member is fitted. The surface of the roller member wears due to friction occurring between it and a sheet or the like. Thus, the conveying roller is preferably configured to be replaceable.
As a solution, an image forming apparatus is known in which a conveying roller is configured to be replaceable. This image forming apparatus includes a conveying roller which is extendable/contractible in the axial direction, and a supporting portion which supports the conveying roller on opposite sides in the axial direction. The conveying roller is composed of a roller (roller member) for conveying a sheet by rotating while in contact with the sheet, a main shaft (roller supporting member) to which the roller is fitted, a sub-shaft (first shaft) fitted to be slidable in the axial direction relative to the main shaft, and an elastic member arranged inside the main shaft for biasing the sub-shaft outward in the axial direction.
In this image forming apparatus, moving the sub-shaft in the insertion direction relative to the main shaft causes the conveying roller to contract in the axial direction, and this makes it possible to easily mount/dismount a conveying roller relative to a supporting portion.